Pharmacokinetics and concentration-effect relationship of anti-TNFα in inflammatory bowel diseases

Les anticorps thérapeutiques ont une pharmacocinétique complexe. Lorsque la masse antigénique augmente, les anticorps thérapeutiques sont éliminés plus vite ; ainsi une maladie active détermine une clairance élevée. De plus, les patients peuvent s’immuniser contre le médicament, produisant des anticorps responsables d’une élimination très accélérée. Dans ce travail, nous avons étudié la variabilité de la pharmacocinétique et de la relation concentration-effet des anti-TNFα dans les maladies inflam-matoires chroniques de l’intestin (MICI). Nous avons décrit par modélisation compartimentale la variabilité pharmacocinétique intra-individuelle de l’infliximab et étudié ses sources, démontrant l’étroite relation entre activité de la maladie et clairance. Nous avons également proposé un modèle capable de détecter les variations de clairance évocatrices d’immunisation indépendamment de la mise en évidence des anticorps anti-médicaments, permettant de s’affranchir du manque de sensibilité analytique de la recherche d’immunisation.Les variations de pharmacocinétique au cours du temps ont été confrontées à la réponse clinique, et nous avons montré que la clairance était prédictive de la réponse en induction et au cours de la désescalade thérapeutique. Nous avons donc proposé que le monitoring des traitements puisse inclure un suivi de l’évolution de la clairance comme marqueur précoce de l’activité de la maladie. Enfin, nous avons montré que l’exposition cumulée était relié au risque d’infection opportuniste dans les MICI. Cela pose les bases de recommandations concernant les modalités d’adaptations poso-logiques qui font actuellement défaut. L’ensemble des travaux présentés ici contribuent à améliorer notre connaissance de la pharmacologie des anti-TNFα et des anticorps thérapeutiques en général et ainsi à optimiser leur utilisation chez les patients.Therapeutic antibodies display complex pharmacokinetic properties. When the antigenic mass increases, they are eliminated faster, and thus an active disease is responsible for a fast clearance. Moreover, patients can produce antibodies to the drug, leading to a strongly accelerated clearance. In this work, we studied the variability of the pharmacokinetics and of the concentration-effect relationship of anti-TNFα antibodies in inflammatory bowel diseases (IBD). The intra-individual variability of infliximab was described using compartmental modelling, and the relationship between disease activity and clearance was demonstrated at the individual level. A model was built to detect clearance increases putatively linked to immunogenicity, independently from evidencing any anti-drug antibodies in blood samples, thus avoiding the analytical issues that hampers the detection of immunization. The time-varying pharmacokinetics was comfronted to the clinical response, showing that clearance was predicitive of the respsonse in induction and de-escalation settings. Therefore, it was hypothetized that monitoring the clearance could help the follow-up of the disease, as an early marker of disease activity and evolution. Last, it was shown that cumulated exposure to infliximab was linked to the risk of developping opportunistic infections. Based on this data, recommandations regarding the modalities of regimen adaptations could be built, that are currently lacking. All the work presented here contribute to enhance our knowledge of the pharmacology of anti-TNFα antibodies, but also of other therapeutic antibodies, and to improve their use in clinical settings

Pharmacocinétique et relation concentration-effet des anti-TNFα dans les maladies inflammatoires chroniques de l’intestin

Therapeutic antibodies display complex pharmacokinetic properties. When the antigenic mass increases, they are eliminated faster, and thus an active disease is responsible for a fast clearance. Moreover, patients can produce antibodies to the drug, leading to a strongly accelerated clearance. In this work, we studied the variability of the pharmacokinetics and of the concentration-effect relationship of anti-TNFα antibodies in inflammatory bowel diseases (IBD). The intra-individual variability of infliximab was described using compartmental modelling, and the relationship between disease activity and clearance was demonstrated at the individual level. A model was built to detect clearance increases putatively linked to immunogenicity, independently from evidencing any anti-drug antibodies in blood samples, thus avoiding the analytical issues that hampers the detection of immunization. The time-varying pharmacokinetics was comfronted to the clinical response, showing that clearance was predicitive of the respsonse in induction and de-escalation settings. Therefore, it was hypothetized that monitoring the clearance could help the follow-up of the disease, as an early marker of disease activity and evolution. Last, it was shown that cumulated exposure to infliximab was linked to the risk of developping opportunistic infections. Based on this data, recommandations regarding the modalities of regimen adaptations could be built, that are currently lacking. All the work presented here contribute to enhance our knowledge of the pharmacology of anti-TNFα antibodies, but also of other therapeutic antibodies, and to improve their use in clinical settings.Les anticorps thérapeutiques ont une pharmacocinétique complexe. Lorsque la masse antigénique augmente, les anticorps thérapeutiques sont éliminés plus vite ; ainsi une maladie active détermine une clairance élevée. De plus, les patients peuvent s’immuniser contre le médicament, produisant des anticorps responsables d’une élimination très accélérée. Dans ce travail, nous avons étudié la variabilité de la pharmacocinétique et de la relation concentration-effet des anti-TNFα dans les maladies inflam-matoires chroniques de l’intestin (MICI). Nous avons décrit par modélisation compartimentale la variabilité pharmacocinétique intra-individuelle de l’infliximab et étudié ses sources, démontrant l’étroite relation entre activité de la maladie et clairance. Nous avons également proposé un modèle capable de détecter les variations de clairance évocatrices d’immunisation indépendamment de la mise en évidence des anticorps anti-médicaments, permettant de s’affranchir du manque de sensibilité analytique de la recherche d’immunisation.Les variations de pharmacocinétique au cours du temps ont été confrontées à la réponse clinique, et nous avons montré que la clairance était prédictive de la réponse en induction et au cours de la désescalade thérapeutique. Nous avons donc proposé que le monitoring des traitements puisse inclure un suivi de l’évolution de la clairance comme marqueur précoce de l’activité de la maladie. Enfin, nous avons montré que l’exposition cumulée était relié au risque d’infection opportuniste dans les MICI. Cela pose les bases de recommandations concernant les modalités d’adaptations poso-logiques qui font actuellement défaut. L’ensemble des travaux présentés ici contribuent à améliorer notre connaissance de la pharmacologie des anti-TNFα et des anticorps thérapeutiques en général et ainsi à optimiser leur utilisation chez les patients

Pharmacogenetics of Membrane Transporters of Tacrolimus in Solid Organ Transplantation

International audienceMembrane transporters play an essential role in the pharmacokinetics of drugs as they mediate exchanges between biological compartments. Tacrolimus is characterized by wide interpatient variability in terms of its pharmacokinetics that may in part be due to genetic factors. The pharmacogenetics of drug transporters is therefore a promising area to explore in the clinical pharmacology of tacrolimus. The aim of this review is to provide an overview of currently available data regarding the pharmacogenetics of membrane transporters that may be involved in the interindividual variability of the response to tacrolimus. Several genetic variants in genes coding for influx or efflux membrane transporters (e.g. ABCB1, ABCC2, ABCC8, SLC30A8, SLCO1B1/3, SLC28A1, SLC22A11, and SLC28A3) have been associated with tacrolimus pharmacokinetics variability or the occurrence of toxicity; however, there is still a degree of controversy as to the impact of these variants in vivo and further investigations are needed to confirm these results in larger cohorts and to validate the relevance of such genetic biomarkers for personalization of immunosuppressive therapy in solid organ transplantations. The relationship between transporter polymorphisms and the intracellular concentration of tacrolimus should also be further investigated. Finally, the main challenge could be elucidation of the interplay of biological mechanisms underlying genetic variations that alter the drug concentration or its clinical effect

Tacrolimus overexposure in kidney transplant recipients during the first post-operative week: caution is required in older patients

International audienceIn liver transplantation, tacrolimus trough concentrations (Cmin) above 20 ng/mL during the first days led to worse outcome at 1 year but data in the kidney transplant (KT) era are scarce. The aim of this study was to evaluate the impact of tacrolimus overexposure during the first week post-transplantation on the kidney function (KF) of KT recipients. In this retrospective study, 105 KT recipients were attributed to overexposure group (OG) or normal group according to their Cmin during the first week of treatment. KF was evaluated by comparing the rate of Delayed Graft Function (DGF) and by collecting plasma creatinine from day-1, 2, 3, 4, 5, 6, 7, 14, 21, 28 and at 1 year. Risk factors for developing DGF were also investigated using a multivariate model. DGF was more frequent in OG (43% of patients) (p=0.027) which has higher plasma creatinine on day-7, -14 and 21. OG patients were older with more extended criteria donor's grafts. In the multivariate analysis, only cold ischemia time (CIT) remained associated with DGF (OR = 1.003), while TAC overexposure did not reach significance (p = 0.06; OR = 3.9). In this study, we confirmed the predominant role of CIT as a risk factor for the onset of DGF in kidney transplantation. 43% of KT recipients were overexposed with more DGF, especially older patients

Modelling of the Time-Varying Pharmacokinetics of Therapeutic Monoclonal Antibodies A Literature Review

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Population Pharmacokinetics of Posaconazole Tablets and Monte Carlo Simulations To Determine whether All Patients Should Receive the Same Dose

International audiencePosaconazole is extensively used for prophylaxis for invasive fungal infections. The gastro-resistant tablet formulation has allowed the bioavailability issues encountered with the oral suspension to be overcome. However, overexposure is now frequent. This study aimed to (i) describe the pharmacokinetics of posaconazole tablets in a real-life cohort of patients with hematological malignancies and (ii) perform Monte Carlo simulations to assess the possibility that the daily dose can be reduced while keeping a sufficient exposure. Forty-nine consecutive inpatients were prospectively included in the study. Posaconazole trough concentrations (TC) were measured once a week, and biological and demographic data were collected. The concentrations were analyzed by compartmental modeling, and Monte Carlo simulations were performed using estimated parameters to assess the rate of attainment of the target TC after dose reduction. The pharmacokinetics of posaconazole were well described using a one-compartment model with first-order absorption and elimination. The values of the parameters (interindividual variabilities) were as follows: the absorption constant (k(a)) was 0.588 h(-1) (fixed), the volume of distribution (V/F) was 420 liters (28.2%), and clearance (CL/F) was 7.3 liters/h (24.2%) with 31.9% interoccasion variability. Forty-nine percent of the simulated patients had TC at steady state of >= 1.5 mu g/ml and maintained a TC above 1 mu g/ml after a reduction of the dose to 200 mg daily. A third of these patients eligible for a dose reduction had TC of >= 1.5 mu g/ml as soon as 48 h of treatment. Though posaconazole tablets were less impacted by bioavailability issues than the oral suspension, the pharmacokinetics of posaconazole tablets remain highly variable. Simulations showed that approximately half of the patients would benefit from a reduction of the dose from 300 mg to 200 mg while keeping the TC above the minimal recommended target of 0.7 mu g/ml, resulting in a 33% savings in the cost of this very expensive drug

Cumulative Exposure to Infliximab, But Not Trough Concentrations, Correlate With Rate of Infection

International audienceBackground & aims: Infliximab increases the risk of infection in patients with inflammatory bowel diseases (IBD), but there is controversy over the relationship between drug concentration and infections. We aimed to assess factors associated with infection in infliximab-treated patients, including pharmacokinetic features.Methods: We collected data from 209 patients with IBD (102 men; mean age, 39 y; 159 with Crohn's disease; 54 received combination therapy) who received a infliximab maintenance regimen from November 2016 through April 2017 in France. Data were collected from each infusion visit (total of 640 infusions). Infliximab exposure was estimated based on the area under the curve (AUC) of drug concentration in pharmacokinetic models; individual exposures over the 6-month period were estimated based on the sum of the AUC (ΣAUC).Results: The mean infliximab trough level was 5.46 mg/L, and the mean ΣAUC was 3938±1427 mg d/L. A total of 215 infections were collected from the 640 infusion visits; 123 patients (59%) had at least 1 infection. Factors independently associated with infection after multivariate analysis were smoking (odds ratio [OR], 2.05; P=.046), IBD flare (OR, 2.71; P=.006), and a high ΣAUC of infliximab (above 3234 mg x d/L) (OR, 2.02; P=.02). The ΣAUC was higher in patients with an occurrence of infection (P=.04) and correlated with the number of infections (P=.04). Trough concentration of infliximab alone was not associated with infection.Conclusions: Almost two-thirds of patients treated with infliximab developed an infection; risk was individually correlated with cumulative increase in drug exposure, but not infliximab trough level

Pharmacokinetic parameters of infliximab influence the rate of relapse after de-escalation in adults with inflammatory bowel diseases

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